Two-phase mass transporting under various operating conditions during mode switching of unitized regenerative fuel cell with non-uniform flow channels

ABSTRACTThe electrolyzing and fuel cell (FC) modes appear in a unitized regenerative FC. Understanding the operating condition impacts on the dynamic behaviors during mode-switching procedure facilitates better handling of cell working states and increasing the performance behaviors. In the present paper, a two-dimensional transient numerical model is employed to discuss the influence of operating conditions on two-phase species distributions when switching the cell mode into FC. According to the numerical results, it is concluded that when the cell switches from electrolytic cell to the mode of FC, reducing the operating cell voltage can significantly improve the cell performance. At the same time, concentration polarization and temperature heterogeneity are serious. Increasing the gas inlet velocity can improve the cell performance. Providing the reaction gas with the same concentration as the FC mode in advance can improve the temperature uniformity and cell current density values when starting switching the mode but hardly impacts the parameter value and currents after stabilization.KEYWORDS: Dynamic responsegas purgingmode switchingtwo-phase mass transferunitized regenerative fuel cell AcknowledgementsThe National Natural Science Foundation of China [Grant No. 51976004] financially supports the present work, and the authors are grateful to Ms. Hai Xin YI for typesetting.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThe work was supported by the National Natural Science Foundation of China [51976004].